IP FRAGMENT PROCESSOR, IP FRAGMENT PROCESSING METHOD AND STORAGE MEDIUM WITH STORED PROGRAM

摘要

PROBLEM TO BE SOLVED: To execute the check sum recalculation processing of an IP header, which is executed in processing an IP fragment, by one software instruction. SOLUTION: Leading eight bytes in the IP header of an original IP packet are stored in an R1 register 101 and the leading eight bytes in the IP header, which are obtained by fragment-processing packets obtained by dividing the original IP packet, are stored in an R2 register 102. A TTL value and an HC value in the IP header of the original IP packet are stored in an R3 register 103. An arithmetic circuit 104 operates a TL value, an FL value and an FO value which are stored in the R2 register 102, from a TL value stored in the R1 register 101. An arithmetic circuit 105 subtracts '1' from the TTL value stored in the R3 register 103 and finds the HC value corresponding to it. An arithmetic circuit 106 adds the operation result of the arithmetic circuit 104 and the HC value found by the arithmetic circuit 105, to obtain the new HC value and stores it in the R3 register 103.